Studies of the Cross Section of Water in the Innermost Areas of Ariake Bay with the Recent Occurrence of Hypoxic Water and Red Tide.

裕昭, 堤; Tsutsumi, Hiroaki; 絵美子, 岡村; Emiko, Okamura; 満代, 小川; Mitsuyo, Ogawa; Takahashi, Tōru; 徹, 高橋; 一岩, 山口; Yamaguchi, Hideyo; 茂, 門谷; Shigeru, Montani; 乃子, 小橋; Kohashi, Naoko; 貴浩, 安達; Adachi, Takahiro; 利光, 小松; Komatsu, Toshimitsu

doi:10.5928/kaiyou.12.291

Cited by 33 publications

(19 citation statements)

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“…The occurrence of hypoxic waters over wide areas of the inner part of Ariake Bay was first observed in August, 2001 (Sato et al 2001, The Nature Conservation Society of Japan 2001, Tsutsumi et al 2003). Since then, hypoxic conditions have been reported every summer (Tsutsumi 2006, Tsutsumi et al 2007, Hamada et al 2008.…”

Section: Introductionmentioning

confidence: 98%

“…Summary of the changes of benthic environment and macro-benthic communities at the four stations (Stn S2 to Stn C) between 2002 and 2008. The data from this study, along with previous related studies (Tsutsumi 2006, Tsutsumi et al 2003, 2005, were collected in the inner part of Ariake Bay between 2002 and 2008. the occurrence of hypoxia (Karlson et al 2002). However, at Stn C, few signs of organic enrichment and reduced conditions of the sediment were found (TOC of the sediment was 6.0±2.2 mg C g −1 in 2008 (Fig.…”

Section: Progress Of Organic Enrichment Of the Sedimentmentioning

confidence: 99%

“…Therefore, the deceleration of the tidal current may have been a key event that induced a series of environmental changes and disturbances in the inner part of Ariake Bay. These environmental changes include more frequent occurrences of phytoplankton blooming in the surface layer of the stratified water (Ministry of the Environment 2006, Tsutsumi 2005, Tsutsumi et al 2003, an increase in the deposition of fine particles on the sea floor (Fig. 5), the progress of the organic enrichment of the sediment (Fig.…”

Section: Accelerated Deposition Of Mud On the Sea Floormentioning

confidence: 99%

“…Both an increase in the frequency and size of red tide events tend to lead to organic enrichment of the sediment through an increase in organic loading on the sea floor, which in turn results in hypoxic conditions due to the increase in oxygen consumption caused by the decomposition of organic matter deposited on the sediment (Diaz & Rosenberg 1995, 2008, Karlson et al 2002, Tsutsumi et al 2003. Here, we define hypoxia as water with dissolved oxygen (DO) levels of less than 3.0 mg L −1 .…”

Section: Introductionmentioning

confidence: 99%

“…Here, we define hypoxia as water with dissolved oxygen (DO) levels of less than 3.0 mg L −1 . In the case of Ariake Bay, the maximum water temperature in summer reaches 28°C to 32°C at the surface, and 26°C to 28°C in the benthic waters (Tsutsumi 2006, Tsutsumi et al 2003, 2005. Macro-benthic animals are more sensitive to the negative impacts of decreases in the DO of the water in such warm conditions.…”

Section: Introductionmentioning

confidence: 99%

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Implications of changes in the benthic environment and decline of macro-benthic communities in the inner part of Ariake Bay in relation to seasonal hypoxia

Tsutsumi

Takamatsu

Nagata

et al. 2015

Plankton Benthos Res

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Abstract:In the inner part of Ariake Bay, located on the west coast of Kyushu, in western Japan, red tides have occurred with more frequency since the second half of the 1990s. Hypoxic waters have occurred during the summer months since the 2000s, despite the fact that nutrient loading from the land to the bay has not increased over the last five decades. We monitored water conditions at nine stations in the inner part of the bay, conducted benthic environmental surveys, and quantitative samplings of macro-benthic communities at the innermost four stations between 2002 and 2008. Each summer, the water was well-stratified due to the development of a halocline and a thermocline. The DO of the water below the pycnocline fell to hypoxic conditions. At the innermost three stations in the bay, the mud content and organic matter content of the sediment increased significantly, and the carbon stable isotope ratios of the organic matter contained in the sediment ranged between −21.3±0.5 and −20.7±0.5 of δ 13 C. These facts indicated that the organic matter was derived photosynthetically from marine phytoplankton. The increase in the mud content of the sediment indicates a deceleration in the tidal current. This may be a key event that induces a series of environmental changes and disturbances, including the stratification of the water, the more frequent occurrence of red tides, the progress of the organic enrichment of the sediment, and the occurrence of hypoxic water during the summer.

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Section: Introductionmentioning

confidence: 98%

Section: Progress Of Organic Enrichment Of the Sedimentmentioning

confidence: 99%

Section: Accelerated Deposition Of Mud On the Sea Floormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Implications of changes in the benthic environment and decline of macro-benthic communities in the inner part of Ariake Bay in relation to seasonal hypoxia

Tsutsumi

Takamatsu

Nagata

et al. 2015

Plankton Benthos Res

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Effects of tidal flat reclamation on sediment quality and hypoxia in Isahaya Bay

Hodoki

Murakami

2006

Aquatic Conserv: Mar. Freshw. Ecosyst.

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1. Ariake Bay, which is located in western Japan, has a large tidal range (>6 m) and a vast tidal flat (200 km 2 ). In the early 1990s, the government-managed Isahaya Reclamation Project began in the western part of Ariake Bay. A 16-km 2 area of tidal flat in the inner part of Isahaya Bay was destroyed through reclamation and separated from the sea by a dyke, which created land and a freshwater reservoir.2. Since the initiation of the project, fishery yields around Isahaya Bay have dramatically decreased. The objective of this study was to clarify the relationship between the work associated with the Isahaya Reclamation Project and the recent environmental deterioration in Ariake Bay, with references to present sediment thickness and organic matter content, and hypoxic water distributions in Isahaya Bay.3. The organic matter load from the reservoir has increased since the initiation of the reclamation project and has been associated with a thick layer of fine sediment at the bottom of Isahaya Bay. The thickness of fine sediment and the total organic carbon content were higher in Isahaya Bay than in the freshwater reservoir.4. Based on measurements in August 2001, hypoxic water spread widely in and around Isahaya Bay; the lowest dissolved oxygen (DO) concentration (0.53 mg L À1) was observed just outside the dyke. An analysis based on a two-layered box model using data obtained in August 2001 showed that the DO consumption rate in the bottom layer was high (0.61 mg O 2 L À1 day À1 ), and that 22-41% of the total organic carbon load needed to induce the hypoxic water was derived from the reclamation area.5. Our findings strongly suggest that enclosed seas may suffer from eutrophic and hypoxic conditions because of their low seawater-exchange rate. A comprehensive conservation programme and environmental assessment including physical and material transport processes in the system is needed to manage the environment of the enclosed sea.

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Biological Richness Of The Asian Tidal Flats And Its Crisis By Human Impacts

Sato

Koh

Ecological Issues in a Changing World

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Studies of the Cross Section of Water in the Innermost Areas of Ariake Bay with the Recent Occurrence of Hypoxic Water and Red Tide.

Cited by 33 publications

References 0 publications

Implications of changes in the benthic environment and decline of macro-benthic communities in the inner part of Ariake Bay in relation to seasonal hypoxia

Implications of changes in the benthic environment and decline of macro-benthic communities in the inner part of Ariake Bay in relation to seasonal hypoxia

Effects of tidal flat reclamation on sediment quality and hypoxia in Isahaya Bay

Biological Richness Of The Asian Tidal Flats And Its Crisis By Human Impacts

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